Space heaters for small compartments and especially for the applications mentioned above have been provided heretofore with an upwardly extending combustion chamber which opens into a flue-gas passage serving as a heat exchanger with the ambient air and having a downwardly extending portion terminating in an outlet for the flue gases. A combustion device, e.g., a burner, can be provided at the base of the combustion chamber. Conventional space heaters of this type thus define a combustion chamber, which is isolated from the ambient air, and may have a combustion air pipe opening upwardly into the device from the bottom. As a consequence, if the available air feed to this inlet is horizontal, the requirement that the inlet open into the bottom of the combustion chamber from directly below the combustion chamber via the upwardly extending portion of the tube, necessitates a comparatively high heating structure.
The outlet previously mentioned can be connected to a chimney or stack or can open directly through the wall of the chamber to be heated.
Problems are encountered in the event the hole cannot be made in the floor of the chamber at the proper location to communicate with the air inlet and where it may be desired to move the heater from one place to another which may not have facilities for such a hole.
In some cases, moreover, it will not even be possible to provide a feed from below to the space heater. This is usually the case in ship cabins and many vehicle cabins.
When the combustion-air feed is from directly below the combustion chamber, a relatively low-lying burner must be provided and the heating surface expansion and contraction phenomenon then extends practically to the floor of the cabin, creating problems with sealing and safety. Furthermore, low-lying portions of the heating surface are generally less effective than heating surfaces disposed well above the floor.